A non-contact charging system is used in a handset of a home cordless phone and the like. In the non-contact charging system, a coil (inductor) is included in each of a power transmission device on the power supply side and a power reception device on the power reception side, energy (electric power) transmitted from the power transmission device is transmitted to the power reception device by mutual induction, and a battery is charged by the transmitted energy.
In this system, the power transmission device cannot detect whether or not the power reception device is present. Therefore, even when the power reception device is not present, the power transmission device has to radiate charging power at all times, so that the power is wasted. Also, the power transmission device cannot obtain information of reception power limit (lower limit of power capable of charging a battery) and charge completion of the power reception device, so that the power transmission device transmits power under a predetermined certain transmission condition. Therefore, the relationship between the power transmission device and the power reception device is usually limited to one-to-one relationship of predetermined devices. Thus, the flexibility of the system is low.